feat: segment sequence support define initial value (#281)

pkg/sequence/segment.go

@@ -33,7 +33,7 @@ const (
 		"    PRIMARY KEY ( `business_id` )" +
 		");"
 	segmentExits  = "SELECT EXISTS (SELECT 1 FROM `segment` WHERE `biz_id` = ?)"
-	insertSegment = "INSERT INTO `segment`(`biz_id`, `step`, `max_id`) VALUES (?, ?, 1)"
+	insertSegment = "INSERT INTO `segment`(`biz_id`, `step`, `max_id`) VALUES (?, ?, ?)"
 	selectSegment = "SELECT max_id FROM segment WHERE biz_id = ? FOR UPDATE"
 	updateSegment = "UPDATE segment SET max_id = ? WHERE biz_id = ? AND max_id = ?"
 )
@@ -47,7 +47,7 @@ type SegmentWorker struct {
 	step   int64
 }
 
-func NewSegmentWorker(dsn string, len int64, biz string) (*SegmentWorker, error) {
+func NewSegmentWorker(dsn string, from, len int64, biz string) (*SegmentWorker, error) {
 	db, err := sql.Open("mysql", dsn)
 	if err != nil {
 		return nil, err
@@ -66,7 +66,7 @@ func NewSegmentWorker(dsn string, len int64, biz string) (*SegmentWorker, error)
 		}
 	}
 	if !exists {
-		if _, err := db.ExecContext(context.Background(), insertSegment, biz, len); err != nil {
+		if _, err := db.ExecContext(context.Background(), insertSegment, biz, len, from); err != nil {
 			log.Error(err)
 			return nil, err
 		}
@@ -103,8 +103,8 @@ func (w *SegmentWorker) ProduceID() {
 			}
 		}
 
-		w.buffer <- w.min
 		w.min++
+		w.buffer <- w.min
 	}
 }
 

pkg/sequence/segment_test.go

@@ -35,7 +35,7 @@ func (suite *_SegmentTestSuite) SetupSuite() {
 		suite.T().Fatal(err)
 	}
 	dsn := fmt.Sprintf("root:123456@tcp(localhost:%d)/segment", port.Int())
-	segment, err := NewSegmentWorker(dsn, 1000, "student")
+	segment, err := NewSegmentWorker(dsn, 0, 1000, "student")
 	if err != nil {
 		suite.T().Fatal(err)
 	}

pkg/sequence/sequence.go

@@ -28,7 +28,7 @@ func NewSequence(generator *config.SequenceGenerator, tableName string) (proto.S
 		if segmentConfig.Step == 0 {
 			segmentConfig.Step = 1000
 		}
-		return NewSegmentWorker(segmentConfig.DSN, segmentConfig.Step, tableName)
+		return NewSegmentWorker(segmentConfig.DSN, segmentConfig.From, segmentConfig.Step, tableName)
 	case config.Snowflake:
 		var (
 			err             error
@@ -49,6 +49,7 @@ func NewSequence(generator *config.SequenceGenerator, tableName string) (proto.S
 
 type SegmentConfig struct {
 	DSN  string `yaml:"dsn" json:"dsn"`
+	From int64  `yaml:"from" json:"from"`
 	Step int64  `default:"1000" yaml:"step" json:"step"`
 }
 

pkg/sequence/snowflake_test.go

@@ -5,6 +5,14 @@ import (
 	"testing"
 )
 
+func TestNextID(t *testing.T) {
+	worker, err := NewWorker(10)
+	if err != nil {
+		t.Error(err)
+	}
+	t.Log(worker.NextID())
+}
+
 func BenchmarkSnowFlakeNextID(b *testing.B) {
 	worker, err := NewWorker(10)
 	if err != nil {